Our Current View of Galaxy Build-up at Cosmic Dawn

Pascal Oesch

Over the last two decades, we have made enormous progress in our exploration of galaxies across comic history. In great part, this was thanks to the revolutionary capabilities of the Hubble Space Telescope, which allowed us to push the observational frontier back to z~11, only ~400 Myr after the Big Bang. To date, we have identified ~1000 likely galaxies at z>6, with up to 20 credible candidates at z~9-11, one of which is even spectroscopically confirmed at z~11. These unprecedented samples allow us to directly track the build-up of galaxies in the heart of the cosmic reionization epoch, providing an increasingly more complete picture. Surprisingly, our current observations are suggesting that bright galaxies were much more common in the early universe than was previously thought. Very wide area surveys - such as the one with HSC - therefore offer an exciting opportunity to find a large number of bright galaxies in the first billion years of cosmic time, promising crucial new insights into early galaxy assembly. In this talk, I will summarize our current view of galaxy build-up at cosmic dawn and I will highlight the exciting possibilities that are just ahead of us based on several major upcoming and planned telescopes.